Only a few features of the solar spectrum have definite discovery dates and acknowledged discoverers. We know that the major dark lines were seen by Wollaston in 1802 and more thoroughly and completely by Fraunhofer himself in 1817. It is known that the first observation of the bright lines in the chromospheric spectrum was by Charles A. Young, of Dartmouth College, in the flash spectrum at the eclipse of 1870; any visible lines which he missed Young saw soon after in his chromospheric searches outside eclipse in 1871 and 1872 -a work which resulted in a catalog of 273 bright lines from 3900 to 7100 A (Young, 1872). For the most part, only coronal lines and inaccessible infrared or ultraviolet features were left for individual discovery. Best known among these are 25303, the coronal green line, found by Young and simultaneously by William Harkness at the 1869 eclipse, and 210747 of Fe xm, the brightest coronal line in the near infrared, found by Lyot with his coronagraph in 1936 (Lyot, 1939).
The circumstances of the first observation of the strongest chromospheric line in the near infrared, 28542 of Ca n, have long been forgotten, if indeed ever known. Charles Young was again the discoverer, at Denver, Colorado, during the eclipse of July 29, 1878. The Princeton party (Figure 1), under Young's direction, searched the coronal spectrum in the infrared with a grating spectroscope and thermopile which were carried on an equatorially mounted board. Resolution in the first order was about 1.6 A at 8000 A. Young was interested in the coronal infrared spectrum as a follow-up of his 1869 work, and he had on hand, as an auxiliary detector, a new invention of Thomas Edison (Eddy, 1972). During the 160 seconds of totality, A. D. Anderson, a graduate student, searched the spectrum by moving the grating with a hand lever, while noting the signal on a reflecting (Thomson) galvanometer. The wooden telescope was directed at different points in the corona by a volunteer assistant from Denver. To Young's disappointment, no infrared coronal lines were found, although "doubtful indications were obtained of a heat line having a wavelength of about 8540 of ~ngstr6m's scale" (Young, 1878). Anderson had noted a repeatable signal increase of 6% at this wavelength on the third of four pointing attempts. Since the feature appeared at but one place, Young classified it as doubtful and apparently forgot about it.